Spin and angular momentum in the nucleon

Using the covariant spectator theory (CST), we present the results of a valence quark-diquark model calculation of the nucleon structure function f(x) measured in unpolarized deep inelastic scattering (DIS), and the structure functions g1(x) and g2(x) measured in DIS using polarized beams and targets. Parameters of the wave functions are adjusted to fit all the data. The fit fixes both the shape of the wave functions and the relative strength of each component. Two solutions are found that fit f(x) and g1(x), but only one of these gives a good description of g2(x). This fit requires the nucleon CST wave functions contain a large D-wave component (about 35%) and a small P-wave component (about 0.6%). The significance of these results is discussed.Comment: 27 pages; 13 figure

Towards the timely detection of toxicants

We address the problem of enhancing the sensitivity of biosensors to the influence of toxicants, with an entropy method of analysis, denoted as CASSANDRA, recently invented for the specific purpose of studying non-stationary time series. We study the specific case where the toxicant is tetrodotoxin. This is a very poisonous substance that yields an abrupt drop of the rate of spike production at t approximatively 170 minutes when the concentration of toxicant is 4 nanomoles. The CASSANDRA algorithm reveals the influence of toxicants thirty minutes prior to the drop in rate at a concentration of toxicant equal to 2 nanomoles. We argue that the success of this method of analysis rests on the adoption of a new perspective of complexity, interpreted as a condition intermediate between the dynamic and the thermodynamic state.Comment: 6 pages and 3 figures. Accepted for publication in the special issue of Chaos Solitons and Fractal dedicated to the conference "Non-stationary Time Series: A Theoretical, Computational and Practical Challenge", Center for Nonlinear Science at University of North Texas, from October 13 to October 19, 2002, Denton, TX (USA

Fixed-axis polarization states: covariance and comparisons

Addressing the recent criticisms of Kvinikhidze and Miller, we prove that the spectator wave functions and currents based on ``fixed-axis'' polarization states (previously introduced by us) are Lorentz covariant, and find an explicit connection between them and conventional direction-dependent polarization states. The discussion shows explicitly how it is possible to construct pure $S$-wave models of the nucleon.Comment: Changed title and introductory material to match accepted pape

Plasma catecholamines during activation of the sympathetic nervous system in a patient with Shy-Drager syndrome.

Plasma catecholamines and circulation parameters were studied in a patient with a Shy-Drager syndrome. Basal values of free noradrenaline and dopamine were within the normal range, whereas the adrenaline level was decreased. The response of plasma catecholamines to different kinds of physical activity was pathological. The inability to maintain elevated catecholamine levels during prolonged activity corresponded to impaired circulatory regulation and may provide an additional tool for diagnosis and monitoring of the Shy-Drager syndrome

Tropical eigenwave and intermediate Jacobians

Tropical manifolds are polyhedral complexes enhanced with certain kind of affine structure. This structure manifests itself through a particular cohomology class which we call the eigenwave of a tropical manifold. Other wave classes of similar type are responsible for deformations of the tropical structure. If a tropical manifold is approximable by a 1-parametric family of complex manifolds then the eigenwave records the monodromy of the family around the tropical limit. With the help of tropical homology and the eigenwave we define tropical intermediate Jacobians which can be viewed as tropical analogs of classical intermediate Jacobians.Comment: 38 pages, 8 figure

Covariant nucleon wave function with S, D, and P-state components

Expressions for the nucleon wave functions in the covariant spectator theory (CST) are derived. The nucleon is described as a system with a off-mass-shell constituent quark, free to interact with an external probe, and two spectator constituent quarks on their mass shell. Integrating over the internal momentum of the on-mass-shell quark pair allows us to derive an effective nucleon wave function that can be written only in terms of the quark and diquark (quark-pair) variables. The derived nucleon wave function includes contributions from S, P and D-waves.Comment: 13 pages and 1 figur

A Nation Deceived: How Schools Hold Back America's Brightest Students, Volume II

Provides a comprehensive review of research on the academic acceleration of gifted students

The String Calculation of QCD Wilson Loops on Arbitrary Surfaces

Compact string expressions are found for non-intersecting Wilson loops in SU(N) Yang-Mills theory on any surface (orientable or nonorientable) as a weighted sum over covers of the surface. All terms from the coupled chiral sectors of the 1/N expansion of the Wilson loop expectation values are included.Comment: 10 pages, LaTeX, no figure

spl(2,1) dynamical supersymmetry and suppression of ferromagnetism in flat band double-exchange models

The low energy spectrum of the ferromagnetic Kondo lattice model on a N-site complete graph extended with on-site repulsion is obtained from the underlying spl(2,1) algebra properties in the strong coupling limit. The ferromagnetic ground state is realized for 1 and N+1 electrons only. We identify the large density of states to be responsible for the suppression of the ferromagnetic state and argue that a similar situation is encountered in the Kagome, pyrochlore, and other lattices with flat bands in their one-particle density of states.Comment: 7 pages, 1 figur

Enumerative aspects of the Gross-Siebert program

We present enumerative aspects of the Gross-Siebert program in this introductory survey. After sketching the program's main themes and goals, we review the basic definitions and results of logarithmic and tropical geometry. We give examples and a proof for counting algebraic curves via tropical curves. To illustrate an application of tropical geometry and the Gross-Siebert program to mirror symmetry, we discuss the mirror symmetry of the projective plane.Comment: A version of these notes will appear as a chapter in an upcoming Fields Institute volume. 81 page